Final answer:
The mass of oxygen reacted in the transformation of a mixture of iron oxides to iron(III) oxide is the difference between the final and initial masses, 0.258 g, corresponding to option (a).
Step-by-step explanation:
The question involves a chemical reaction where a mixture of iron oxides (Fe₃O₄ and FeO) is heated to form iron(III) oxide (Fe₂O₃). We need to find the mass of oxygen that reacted during this process. The initial mass of the mixture is 3.939 g, and the final mass of Fe₂O₃ is 4.197 g. The mass of oxygen reacted is simply the difference between the final mass and the initial mass. Hence, the mass of oxygen reacted is 4.197 g (final mass) - 3.939 g (initial mass) = 0.258 g, which corresponds to option (a).